1. Field of the Invention
This invention relates to automotive shock absorbers in general and more particularly to a piston assembly for such shock absorbers.
2. Disclosure Information
Automotive shock absorbers of the fluid damper type have been in use for many years. The most common configuration for these devices includes a hollow cylindrical working chamber which telescopically receives a cylindrical piston incorporating valving. Most commonly the working chamber is attached to a moving part of the vehicle's suspension such as a lower control arm, whereas the piston is connected to the vehicle's frame or body by means of a piston rod.
The shock absorber is thus interposed via the suspension system between a roadwheel and the vehicle's frame or body. Vertical motion of the roadwheel resulting from either imperfections in the road surface or from roll of the vehicle's body during cornering maneuvers or the like causes a corresponding extension or contraction of the shock absorber along its major axis. This extension is often termed "rebound" or the "rebound stroke", while the contraction motion is termed "compression" or the "compression stroke". During rebound, fluid flows from above the piston and through ports and associated valving contained in the piston until the space below the piston is reached. During compression, fluid flows from below the piston and again through ports and associated valving until the space above the piston is reached. In this application, the term "port" denotes a fluid conducting channel running between the upper and lower faces of the piston.
Shock absorbers are employed in automotive suspensions for the purpose of improving vehicle ride and handling characteristics. For example, shock absorbers assist in controlling body lean on corners and help eliminate the transmission of road induced vibrations to the vehicle body.
A variety of valving systems have evolved for use with shock absorbers of the type with which instant invention is concerned. One example is disclosed in U.S. Pat. No. 4,203,507 to Tomita, et al. Tomita discloses an axially-drilled piston with compression and rebound ports and flow governing means generally comprising annular discs of varying configuration. Similarly, U.S. application Ser. No. 318,646, filed Nov. 5, 1981, now abandoned, assigned to the assignee of this application, discloses another of my inventions directed toward an axially-drilled shock absorber piston having annular flow-governing discs.
Another type of shock absorber piston design is characterized by cross-drilled compression and rebound ports. U.S. Pat. No. 2,316,924 to Whisler and U.S. Pat. No. 4,004,662 to Sorgatz et al each disclose designs of this latter type. The instant invention is directed to an improved cross-drilled shock absorber piston assembly.